Problems

  • Recent Problems

    How many different triangles are there in the figure?
    Problems
    Grades: 3rd to 5th
    Geometry
    Classify two-dimensional figures into categories based on their properties.
    5.G.B.4

    It’s not too hard to form the number 9 using three 3’s and any of the four standard mathematical operations +, –, × and ÷. But can you come up with four different solutions, each of which uses only one of the four operations? (Other standard mathematical symbols can be used as needed.)

    9 = 3 + 3 + 3  

    Problems
    Grades: 3rd to 5th
    Algebraic Thinking
    Write and interpret numerical expressions.
    Multiply and divide within 100.
    3.OA.C.7, 5.OA.A.1
    When the ends of the rope at left are pulled in opposite directions, how many knots will be formed along the rope's length?
    Problems
    Write 2014 with the first four prime numbers, with the aid of the operations addition, multiplication and exponentiation.
    Problems
    Grades: 6th to 8th, 3rd to 5th
    Expression/Equation
    Algebraic Thinking
    Apply and extend previous understandings of arithmetic to algebraic expressions.
    Gain familiarity with factors and multiples.
    Multiply and divide within 100.
    3.OA.C.7, 4.OA.B.4, 6.EE.A.1

    Equations to solve in your head:

    \begin{array}{l}
 6,751x + 3,249y = 26,751 \\ 
 3,249x + 6,751y = 23,249 \\ 
 \end{array}

    Is this a joke? Not if you can multiply the first equation by 6,751 and the second by 3,249 in your head, and not if you use a second, simpler method.

    Problems
    Grades: 9th to 12th, 6th to 8th
    Algebra
    Expression/Equation
    Reasoning with Equations and Inequalities
    Analyze and solve linear equations and pairs of simultaneous linear equations.
    8.EE.C.8b, HSA-REI.C.6, HSA-REI.C.5
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